1. Field of the Invention
The present invention relates to an endoscope system that forms an image of light from an objective optical system provided for an endoscope on two image pickup devices.
2. Description of the Related Art
In recent years, endoscope systems using an endoscope equipped with an image pickup device are widely used in medical and industrial fields.
Furthermore, since a depth of field generally becomes narrower as the number of pixels of the image pickup device increases, there are various proposals relating to this problem.
As a first conventional example, Japanese Patent Application Laid-Open Publication No. 9-116807 discloses an image pickup apparatus that includes an image pickup device arranged at a focus position and at least one image pickup device arranged at a position shifted from the focus position within a range in which a range of depth of field thereof has an area common to a range of depth of field of the image pickup device arranged at the focus position, extracts a high-frequency signal component from an output signal of the at least one image pickup device and performs signal processing of adding the high-frequency signal component to an output signal of the image pickup device arranged at the focus position.
Furthermore, as a second conventional example, Japanese Patent Application Laid-Open Publication No. 2003-78802 discloses an image pickup apparatus including an image pickup device drive apparatus that divides an optical path of light that passes through an image pickup lens that picks up images of objects located at different distances into a plurality of optical paths using optical path dividing means, arranges image pickup devices having different focus positions in the divided respective optical paths and moves the respective image pickup devices along an optical axis direction, a calculation processing apparatus that determines positions on the optical axis of the respective image pickup devices in accordance with an inputted lens parameter of the image pickup lens, and an image synthesis apparatus that synthesizes video signals outputted from the respective image pickup devices.
As a third conventional example, Japanese Patent Application Laid-Open Publication No. 2007-313166 discloses an endoscope that includes a focus adjustment mechanism for capturing a high quality image and two-plate image pickup units arranged by being shifted by approximately ½ pitch pixel in horizontal and vertical directions, in which the vertical direction pixel pitch of the image pickup device and an F number of the objective optical system are set so as to satisfy a predetermined condition.